EP1759780B1 - Multi-stage deep-drawing forming apparatus with independently controlled stages - Google Patents

Abstract

A high-performance deep-drawing multi-stage (2a, 2b, 2c) metal stamping and bending assembly has a rigid outer frame (1). Each stage has an upper and lower section supporting a tool (14-17) operated by an actuator (A) linked to a freely programmable electronic control unit (C).

Description

The invention relates to a step-forming machine specified in the preamble of claim 1 Art.

For stepwise forming of parts usually progressive presses are used. In this case, problematic part geometries can be associated with high precision requirements, difficult to transform materials such as high-strength steels or lightweight materials to be processed, in small, medium or large lot sizes. Deep drawing presses known in the art, e.g. for deep drawing by single-acting pulling, double-acting pulling, everthing, and the like. Most include common to all stages press ram, which specifies the stroke, the acceleration, the speed profile and the force profile for all stages. Setting up the tools is time consuming and requires skilled personnel. Process stability is not very high, at least in some stages, because conventional die cushions or springs are used and the individual stages interact.

Furthermore, it is known to use individual cam drives in step presses for the steps, wherein working in at least some stages in the lower sections against springs or die cushion. The cams controlling the movements do not allow to change stroke and stroke position, the acceleration function, the speed profile and the force profile in individual stages, so that setup or conversion processes are extremely time-consuming and cost-intensive. The tools usually have to be complicated and expensive. High-strength materials and lightweight materials are difficult to process. Complex part geometries require extremely high effort. The draw ratio is limited, so that many steps may be needed for a high degree of deformation. Writing out difficult geometries is hardly possible. The known systems are inflexible and do not allow a modular, reconfigurable machine structure.

Furthermore, it is known from practice to drive a die cushion by a plurality of servo-controlled hydraulic axes in large-scale single-stage deep drawing of body parts or kitchen sink.

The out US Pat. No. 6,520,074 B1 Known step-forming machine with CNC control device has in the different processing steps exporting stages, which are formed of modular press units, electric servomotors, which actuate slides via gears and screw spindles. The control device is programmable so that fast delivery strokes are driven, and that then continues slowly after a stopover. Certain motion patterns are programmed, which are processed by the servomotors.

In one US 2002/0157556 A known transfer press with, for example, four press sections, a main drive motor is provided which drives the individual slides via flywheels, clutches, brakes and crank mechanisms.

At one off EP 1 245 302 A known profiling with several arranged in line forming stations servomotors are provided in the forming stations for pairwise cooperating roll forming tools. Between the tools and the servomotors gears and shafts are arranged. The setting of the roll forming tools via spindle drives. A central data processing device controls all adjustable roll forming tools. From temporal progressions of the position data during a trial phase and temporal progressions of shape data of a profile, process behavior patterns are developed in order to regulate optimal process parameters.

Out GB 1 491 143 A discloses a servo-controlled hydraulic pressing device for deep-drawing seamless cup members, which performs operations in four sections within a common press frame, with each of which a final product is produced. As actuators multi-stage hydraulic cylinders are used with control valves. The control device is a logic circuit which controls the working steps in consideration of signals of limit switches or stroke measuring devices. Each thermoforming process is executed, but not regulated. For example, the hold-down formed by a hydraulic cylinder stage with constant contact pressure operated. Limit switch report to the controller, the execution of the relevant step, wherein at least no pressure measurement is performed. In the control device wave generators are provided as clock for all sections of the pressing device. Only relatively simple end products are produced.

The invention has for its object to provide a step-forming machines of the type mentioned, the short Einrichtzeiten, easy readjustment, high process stability and a flexible modular machine structure allows, and in particular can use all the usual thermoforming methods.

The stated object is achieved with the features of claim 1.

Due to the free and independent programmability different strokes, stroke positions, force profiles and / or velocity profiles can be realized in the stages. The forces used in the stages act without tilting influence by adjacent stages. The setup processes of the tools only require fractions of the usual times. Significant tool cost savings are possible. High-strength materials and lightweight materials are much easier to process, since the programming is adapted to the process-related requirements. The course of the movement and / or the course of the force and / or the course of the speed can be adjusted individually in each stage to the criteria which are decisive for this stage. It is possible to increase the respective drawing ratio, which saves steps. The geometry of a part can even be pronounced because the tool can remain in the final position or even look up. Mutual influencing of the steps is avoided. It is a flexible, modular machine design possible because each stage can be integrated as a module in the step-forming machine. Here, a die cushion or a drawing spring is replaced by the programmable hydraulic cylinder, which is not only precisely adjustable its initial force effect, but also allows a programmable force curve or path, which is not limited by any progressiveness, but for optimal forming, eg deep drawing , cares. This means that not only can the initial force effect in the cycle possibly even be withdrawn, but the further force, travel or speed profile of the hydraulic cylinder can be freely optimized during the cycle, ie largely independent of the cycle sequence in the associated other section. Every actuator is at least a hydraulic cylinder with at least one associated control valve, which is accessed by the electronic control device. Hydraulic cylinders allow the development of optimal stroke, acceleration, speed and force profiles in a compact size, so that each stage operates under optimized conditions. The generated pressure and the applied force are proportional to each other. This is particularly useful for deep drawing. The control valve, expediently a servo or proportional valve with magnetic actuation, allows the sensitive and optionally load-independent motion control of the respective tool. Each hydraulic cylinder defines, as it were, a servohydraulic CNC axis in any arrangement, ie in the upper and / or the lower section of the respective stage. Each hydraulic cylinder is either operated only with a travel control, or with a displacement and pressure control. In the latter case, during a work cycle, a changeover from displacement to force regulation and vice versa can take place. The time of switching, for example, to a force control and then the force profile to be controlled are programmed in the CNC program by the installer. Thanks to the free programmability, the geometry of a part can even be pronounced, in which, for example, the drawing punch remains in the end position or even looks up. This allows the hydraulic cylinder in the actuator problems, because the individual stages do not affect each other at all. The change-over from, for example, displacement to force control, and vice versa, is programmed via a so-called multi-cam function and thereby visualized in the programming terminal. For example, the two working axes of a section with the one or two working axes of the other section of the stage are displayed and programmed together in the terminal.

In order to avoid fluctuations in the working cycles and to ensure a high process stability, it is expedient if the distance measuring device and / or the pressure measuring device to a control stage, in particular a PID controller, connected, wherein the control stage between a setpoint generator and the control valve is placed. It is e.g. a feedback control in a closed loop.

Because it is important, thanks to the individual and free programmability in adaptation to the desired work result of each stage, to control the work cycles exactly reproducible, possibly the respective stroke or stroke, the force or the force curve, an acceleration function or a speed profile during the work cycle to vary or switch between certain procedures, ie first build a certain force and then change the velocity profile, it is useful if each hydraulic cylinder is associated with a distance measuring device and / or a pressure measuring device which is directly or indirectly connected to the electronic control device or are, so that the electronic control device is informed at any time about the actual conditions. For example, an absolute displacement sensor is associated with the movement of the tool or a movable component of the hydraulic cylinder as the path measuring device. The pressure measuring device may be an analog or digital transducer, which picks up the pressure, for example in the cylinder, and converts it into a signal for the electronic control device.

For convenient handling during free programming, it is expedient if the electronic control device comprises a programming terminal with a monitor. The monitor enables the visualization of the programming of each individual working axis. The entire process can be visualized in a diagram in order to be able to carry out temporal reconciliation of the individual processing steps in the simplest way. When setting up a new tool, the steps are stacked on each other, e.g. on the programming terminal, tuned, and not on the built-in or removed tool. The installation of a tried and tested tool is also carried out with a process coordination at the terminal.

Suitably, each hydraulic cylinder defines a working or tool axis, with up to four working axes per step. Each individual movement can be programmed, both the forward stroke and the return stroke, or the common strokes in the upper and lower sections during a work cycle. During deep drawing, the four axes can include, for example, the die, the drawing punch, the sheet metal or blank holder and an ejector. This allows all common thermoforming methods to be used, with each movement being programmed.

Per section, ie below and / or above, a maximum of two hydraulic cylinders should be provided. These hydraulic cylinders can be built into each other coaxially, or integrated into the actuator one behind the other. This saves space and allows you to process as many steps as possible in each step.

Advantageously, the steps in the frame in modular design individually interchangeable and / or implemented arranged. This allows the step forming machine to be conveniently configured to make other parts or use other tools.

In an advantageous embodiment, a monoblock forming machine is provided, in which all stages are arranged in a single frame into which the raw material enters and from which the parts are conveyed away.

In an alternative embodiment, a multi-block automatic forming machine is used from a plurality of frame racks, each with selected stages, which are coupled together as a complete forming center. Intermediate machining may be performed between the individual blocks if necessary.

In a particularly expedient embodiment, each stage is arranged in a frame frame section, which can be exchanged with other frame sections to a monoblock or Mutliblöcke combined. This step module system is extremely flexible and reconfigurable. In a framework section could also be housed more than one stage.

In an expedient embodiment, the frame frame section is a C-shaped single column frame with an open mouth side and a stand. The Einständergestell is optionally placed with its sides in a composite with other stage modules, the mouth sides can be conveniently clamped vertically with tie rods to minimize springing of the frame section in operation.

It is advantageous in this case to arrange in each case adjacent step modules offset by 180 ° relative to one another, so that the open mouth sides point to opposite sides. The composite with each adjacent step module is force-transmitting purposefully provided only near the mouth sides, where pinning, clamping elements or fittings prove to be useful. The upper and lower cheeks of Einständergestells are expedient only in the front area, ie near the end faces the cheeks connected to the neighboring frame to avoid mutual interference by the deflection of adjacent individual racks. If necessary, the step modules can be replaced individually or used in addition. Alternatively, all or most of the mouth sides could point to the same side. The springing of the mouths could then be prevented for example by tie rods or tensioning devices.

The respective monoblock or multiblock of step modules is advantageously completed at both ends of a set of single-stand racks by end-pieces which are used as e.g. single-stage double-stand sections are formed. This creates a longitudinal tunnel through which the transfer system can be installed. The principle of the step modules enables an extremely flexible reconfigurability of the step press. Such double column sections (with one or more stages) could also be used internally in the step module system, if e.g. the unilaterally open C-construction is not appropriate at this point.

Regardless of whether it is a monoblock version or a step module system, or whether step modules are used, the step forming machine can be combined with automatic follow-up processing devices for mounting, welding, threading, joining or the like.

Fig. 1

eine schematische Frontansicht eines Stufen-Umformautomaten, insbesondere eines Tiefzieh-Umformautomaten, in einer sogenannten Monoblock-Konfiguration,

Fig. 2

eine zugehörige Draufsicht zu Fig. 1,

Fig. 3

eine schematische Frontansicht eines Stufen-Umformautomaten in einer Multiblock-Konfiguration,

Fig. 4

ein Detailschema, perspektivisch, zur Verdeutlichung des Aufbaus eines Stufenmodulsystems und einer Stufen-Modulkonfiguration,

Fig. 5

ein Aktuator einer Stufe im Schnitt, und

Fig. 6

ein Blockschaltbild, zu einer zweiachsigen Sektion einer Stufe.

With reference to the drawings, embodiments of the subject invention will be explained. Show it:

Fig. 1

a schematic front view of a step-forming machine, in particular a deep-drawing forming machine, in a so-called monobloc configuration,

Fig. 2

an associated plan view too Fig. 1 .

Fig. 3

a schematic front view of a step-forming machine in a multi-block configuration,

Fig. 4

a detailed scheme, in perspective, to illustrate the structure of a step module system and a stage module configuration,

Fig. 5

an actuator of a stage on average, and

Fig. 6

a block diagram, to a biaxial section of a stage.

One in the Fig. 1 and 2 shown step-forming machine S, for example, a thermoforming forming machine in monobloc configuration M, has a closed frame 1, for example made of steel, which is open at both ends for material supply and part removal, and at the front and, if necessary. Rear free access offers. In the rack 1, a plurality of stages 2a, 2b, 2c, etc. are accommodated in succession and processing, each stage comprising an upper section 4 and a lower section 5. Furthermore, in the step-forming machine S, a transfer system T, expediently provided with unspecified servohydraulic or servo-electric drives, which can be equipped, for example, with grippers 3 for one-sided operation. In each stage 2a, 2b, 2c at least one servohydraulic actuator A is included, possibly even in each section 4, 5. Furthermore, an electronic control device C, expediently a CNC control device for free programming of at least the stages 2a, 2b, 2c, and optionally also of the transfer system T, which comprises at least one programming terminal 7 with a monitor 6. Further, an electro-hydraulic supply unit 8, for example, a motor-pump unit for providing sufficient hydraulic pressure and sufficient flow rate for the actuators A stages is provided, which is optionally associated with the electronic control device C and / or the programming terminal 7.

In the stages 2a, 2b, 2c in the Fig. 1 and 2 , each section 4, 5 may have at least one servo-hydraulic actuator A, or only the lower or upper section 4, 5. All stages are completely independent of each other freely programmable and can with different strokes or strokes and / or forces or force profiles and / or speeds or speed profiles work.

Alternatively (not shown), electromagnetic drives (e.g., with associated servo drives) could be used as actuators A.

Even problematic parts geometries with high precision requirements can be produced. Furthermore, e.g. to process difficult-to-form materials such as high-strength steels or lightweight materials during thermoforming. The free programmability allows minimal set-up times, so that the transfer press is particularly well suited for small and medium lot sizes.

Fig. 3 schematically illustrates a multi-block configuration MU of the step-forming machine S. Several frame racks 1, each with selected stages 2a, 2b, and the like., Are consecutively set in the production direction and interconnected via intermediate transfer devices 9. The multiblock configuration allows a reconfigurable arrangement and is therefore particularly flexible to adapt to changing requirements.

Fig. 4 illustrates a step-by-step system operating in either the monobloc M configuration of Fig. 1 or in the multiblock configuration MU of Fig. 3 can be applied. Each step 2a, 2b is integrated in a step module, which is designed as a C-shaped Einstufengestell 11 and open at a mouth side. Adjacent Einstellgestelle 11 are installed, for example, offset from each other by 180 °, such that the mouth sides have to different sides. Suitably, the upper and lower cheeks of each Einständergestells 11, suitably close to the respective cheek end and as indicated at 13, positively connected to the adjacent Einständergestell 11, eg pinned, cocked or screwed, so that the Einständergestell 11 does not auffedert in operation. This only local frictional connection eliminates the risk of mutual interference of Einständergestelle by deflections. At the ends of such, several Einlständergestelle 11 having composite end portions 10 are suitably connected in the form of double-column modules. A central tunnel 12 is defined in which the transfer system T can be installed. The mouth sides could also be the same Side and be stabilized by tie rods or fixtures. If necessary. At least one double column module 10 is housed inside the step module system.

Fig. 5 illustrates a stage, for example, the stage 2b, which in the upper section 4 and in the lower section 5 each have a working axis X and Y respectively.

As a tool of the upper section 4, for example, a die 14, driven by a hydraulic cylinder 27, and a central ejector punch 15, driven by a hydraulic cylinder 26 are provided, wherein the hydraulic cylinders 26, 27 coaxially with each other or one behind the other are set and the servohydraulic actuator A. define.

In the lower section 5, two tools are also provided, namely a plate or hold-down 16, driven by a hydraulic cylinder, and a drawing punch 17, also driven by a hydraulic cylinder, the two hydraulic cylinders are coaxially in the servohydraulic actuator A summarized.

Each hydraulic cylinder is associated with at least one control valve, suitably a servo or proportional control valve. The control valve is actuated by the electronic control device C in dependence on the programming and the control deviation, wherein the hydraulic pressure comes from the hydraulic system 8.

Fig. 6 illustrates a section of a block diagram of the control device for the section 4 of the stage 2b. The lower, not shown here section can be designed the same circuit design. In the monitor 6, for example, control panels 18, 19 and 20 are provided for a Wegachsenprofil, a multi-cam and a profile of the pressure control, which are associated with the hydraulic cylinder 26, the Wegachsenprofil and the analog axis profile of the pressure control 20 each a controller 21 for the way and 22nd are preceded by the pressure as a reference variable. The two regulators are alternatively effective via a switchable in the control panel 19 for the multi-cam switch 23 and to a proportional control valve V of the hydraulic cylinder 26th connected. The actual pressure is detected and converted in a converter 24 into a signal for the pressure regulator 22. Furthermore, the hydraulic cylinder 26 is associated with a distance measuring device 25, for example, an absolute displacement sensor, which provides the controller 21 for the way a signal corresponding to the position or the path. The hydraulic cylinder 26 serves to control the tool 14, for example the die 14 in FIG Fig. 5 while the other hydraulic cylinder 27 for controlling the tool 15, for example, the ejector punch 15 in Fig. 5 , serves. When hydraulic cylinder 26, the same arrangement of control panels and the like. As in the hydraulic cylinder 27 is provided. By setting on the control panel 19 for the multi-cam, for example, the time can set at which is converted from a path control to a pressure control (path profile to pressure profile) during a work cycle, or vice versa. Each hydraulic cylinder can either only work with a travel control, or with travel and pressure control. If an actuator is equipped for the combination of the controls, a changeover can take place within one cycle. The timing of the changeover and the force profile to be controlled are freely programmed by the fitter or machine operator.

Below is an appropriate selection of programming.

In the path control not only the total stroke can be programmed, but even the starting point and end point of the stroke within one cycle. Furthermore, certain positions within the stroke may be programmed, possibly taking into account or changing other criteria, such as pressure or speed. The travel programming, optionally combined with the pressure, can be used to vary the speed within the work cycle (velocity profile) or rapid acceleration to a certain point followed by slow speed under increased or decreased force, and the like. The movement sequence with regard to the path and the pressure can be adapted individually to the respective requirements during forming. To express a particular part geometry, a tool can remain stopped in a certain position with a defined force, or even look up. As a result, draw levels can be saved, which only serve the purpose of calibration in conventional deep drawing. The counterforce of the hold-down, for example in the lower section can be variably set with increasing deformation unlike conventional die cushion or springs. Particularly useful, the force curve in, for example, the lower section during the work cycle gradually decreasing or increasing programmed or even vibrating. The stroke in the lower section can also be adjusted individually. Since each CNC axis is freely programmable, the respective draw ratio can be increased in order to save a total of stages.

Claims (11)

1. Stage-type automatic forming machine (S) having, in a framework (1), a number of stages (2a, 2b, 2c) which carry out different processing steps, wherein each stage has a lower and an upper section (4, 5) and at least one actuator (A), which is supported in the framework and displaces a tool (14 to 17) within a working axis (X, Y), is provided in at least one section of each stage, and an electronic, programmable CNC control apparatus (C) is associated with all the actuators,
   characterised in that each actuator (A) has at least one hydraulic cylinder (26, 27) with at least one associated control valve (V) which is connected to the control apparatus (C); that the travel of the tool and/or the force of the tool and/or the speed of the tool is/are generated by means of the quantity of pressurised hydraulic medium fed to the hydraulic cylinder (26, 27) via the control valve (V); that the travel of the tool and/or the force of the tool and/or the speed of the tool is/are freely programmable for each stage (2a, 2b, 2c); and that, within a processing step, it is possible, via a changeover system with a programmed changing-over time, to change over between regulation of the travel or speed of the tool and regulation of the force of the tool.
2. Stage-type automatic forming machine according to claim 1,
   characterised in that there are associated with each hydraulic cylinder (26, 27) a travel-measuring device (25) and a pressure-measuring device (24) for the force exerted, which is proportional to the pressure, which devices are connected directly or indirectly to the control apparatus (C); that a travel-regulator (21), preferably a PID regulator, which is disposed between a travel set-point transmitter (18) and the control valve (V), is provided for connecting the travel-measuring device (25); and that it is possible, via a changeover switch (23) which is actuated when changing-over occurs, to change over between the regulators (21, 22) which operate alternatively.
3. Stage-type automatic forming machine according to claim 2,
   characterised in that the travel-measuring device (25) has an absolute travel transmitter which supplies an output signal for the travel-regulator (21), and the pressure-measuring device (24) has a pressure-sensing element and pressure-transducer which supplies an output signal for the pressure-regulator (22).
4. Stage-type automatic forming machine according to claim 1,
   characterised in that each hydraulic cylinder (26, 27) defines a working axis (X), and that up to four working axes (X, Y), preferably a maximum of two hydraulic cylinders (26, 27), are provided per stage (2a, 2b, 2c).
5. Stage-type automatic forming machine according to claim 1,
   characterised in that the hydraulic cylinders (26, 27) of the section (4, 5) are placed either coaxially within one another or behind one another in the axial direction.
6. Stage-type automatic forming machine according to claim 1,
   characterised in that the stages (2a, 2b, 2c) are disposed in an interchangeable and/or transposable manner in the framework (1) of a stage module system with a modular type of construction.
7. Stage-type automatic forming machine according to claim 1,
   characterised in that, in a monobloc automatic forming machine (M), all the stages (2a, 2b, 2c) are disposed in a single framework (1).
8. Stage-type automatic forming machine according to claim 1,
   characterised in that, in a multi-bloc automatic forming machine (MU), a number of frameworks (1) contain selected stages (2a, 2b, 2c) in each case, and are coupled to one another as individual forming centres.
9. Stage-type automatic forming machine according to claim 1,
   characterised in that a stage (2a, 2b, 2c) is disposed in a stage module (11) which can be combined interchangeably with other stage modules (11) to form a monobloc automatic forming machine or a multi-bloc automatic forming machine, and that the stage module (11) is a C-shaped single-column frame with an open jaw side, which frame can be brought, with its sides, into an integrated system with other stage modules.
10. Stage-type automatic forming machine according to claim 9,
    characterised in that single-column frames (11) which are adjacent in each case are offset by 180° in relation to one another and are supported against one another, preferably pinned, clamped and/or bolted (at 13), in a force-transmitting manner in the end regions that adjoin the jaw sides.
11. Stage-type automatic forming machine according to claim 10,
    characterised in that closing parts (10) in the form of double-column modules are attached at least at both ends of a group of single-column frames.

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